In a conventional TAB process, a tape made of Kapton, for example, acts as a carrier for semiconductor dies that are mounted thereon. Each die occupies a predetermined "site" on the tape, and each site typically includes conductive metal patterns which connect electrical contacts on the die to conductive test pads formed on the tape. With this arrangement, test equipment probes can be connected to the test pads on the tape in order to test the die before it is removed from the tape and permanently mounted on a substrate, a printed circuit board, or the like.
If the tape-mounted die proves to be defective during the above-mentioned test, the part of the tape defining the site for the defective die cannot be reused. Thus, a defective die results not only in the loss of a die, but also the loss of a relatively expensive die site.
Another drawback to conventional TAB techniques arises from the fact that a die which passes its tests, and then becomes permanently mounted on a substrate, is not protected from the environment. An additional step, such as potting, is required to seal the die from environmental contamination.